Apparatus for the production of music



E. F. MnEsSNER Z- APPARATUS FOR THE PRODUCTION OF MUSIC original Filed June 1, 1932 2 she'ebs-sheei l fr!" /50 IE@ mi?? 5 E2. F. MIESSNER ZOOM APPARATUS FOR THE PRODUCTION OF MUSIC original Filed June i, 1932 2 sheets-sheet 2 IN V EN TOR:-

Patented Jon. 7, 1936 UNITED STATES PATENT OFFICE Benjamin F. Miessner, Mllburn, N. J., assigner to Miessner New Jersey Inventions, Inc.,

a corporation of Application June 1, 1932, Serial No. 614,694 Renewed August 26, 1935 17 Claims.

This invention relates to the production of music from tuned vibrators, and more particularly to such production by means of vibrationoscillation-sound (mechanico-electro-acoustic) translation. In my co-pending application, Serial Number 512.399,' iiled January 30, 1931, (on which U. S. Patent No. 1,929,027 has now been issued) I disclosed and claimed instruments producing music in this manner, together with various mechanica-electric translating means and methods for use therein. 'I'he instant application is directed to improvements in those means and methods; and to instruments wherein such improvements are employed, with other features, in the selective production of a variety oi types of output tone.

Thus it is a broad object of the instant invention to provide improved means and methods for translating the vibrations of tuned vibrators into electric oscillations. It is an allied object to provide an instrument by which a variety oi types of output tone may be selectively produced.

Individual objects of the invention are the provision of improved and simplified means and methods for producing respectively piano-like, organ-like and further types of tones by an instrument of the class described. Other and allied objects will more fully appear from the following description and the appended claims.

In the detailed description of my invention hereinafter set forth, reference is had to the accompanying drawings, of which:-

Figures l, 2 and 3 are respectively plan, end and side views of a simple embodiment of a portion of my invention, Figure 1 including a schematic showing of certain associated electrical and electro-acoustic apparatus;

Figure la is a view similar to Figure l, but illustrating a particular connection for a plurality of' vibrators;

Figure 2a is a view alternative to Figure 2, illustrating a readjustment of one of the parts;

Figure 4 is a plan view of a portion of an instrument, for example oi the grand piano type, embodying my invention, this ligure including a schematic showing of electrical apparatus;

Figure 5 is a cross sectional view taken along the line 5 5 of Figure 4;

Figure 6 is a schematic illustration of certain of the apparatus of Figures 4 and 5; and

Figures 6a and '7 are further schematic illustrations alternative to Figure 6.

In the co-pending application above referred to, I showed broadly an electrostatic mechanicoelectric translating system wherein an electrical capacity was formed between a vibrator and a conductive member and was varied in value by the vibration of the vibrator. A relatively constant charge was maintained in this capacity; and the vibratory variations of duced an oscillatory component in the voltage across the capacity, which component was employed for the actuation or further apparatus. The particular form o1' capacity which I therein showed comprised a portion of the vibrator and a conductive member toward and away from which the vibrator vibrated. In one embodiment of the instant invention, however, I form the charged capacity between the vibrator and a conductive member having a surface assymetrically arranged with respect to the vibrator and principally parallel to which the vibrator vibrates. In another embodiment I form the charged capacity between two stationary conduc- -tive lmembers and vibrate the vibrator so as to intercept at least a portion of the electrostatic eld between the two members. Various considerations establish the desirable relative positions and forms Aoi? the components of these capacities; and these are hereinafter described, with particular reference to strings as vibrators.

Reference being had to Egures 1, 2 and 3, there will be seen a string l and hammer 5 for vibrating it in a vertical plane. Conductive studs 2 and 2', which may be similar to each other, are seen on either side of the string. The studs may be essentially rectangular in horizontal cross-section, and may be formed with a threaded lower portion 3. This portion may be mounted for example by screwing into threaded holes in bakeiite or other insulating strip e. In Figures 2 and 3 the studs 2 and 2 are shown extending above the string i; but by rotation thereof they may be caused to assume various other vertical positions with respect to the string, as forexample that shown in Figure 2a, wherein the studs are seen wholly below the level of the string. The formation of the studs `with rectangular cross-section also permits ready variations of the distances of stud from string. Thus. assuming the longer dimension of the stud head to be rst parallel to the string, rotation of the stud within a 90 arc or less will vary the lateral string-stud separation from a maximum to a minimum of zero value.

In Figure 1, with switch 6 set as therein shownl the charged capacity is that between the string I and the stud 2. It is charged by battery or other potential source l through high resistance 8. This resistance prevents the charge in the the capacity pro- 5 Sii 2 capacity from altering rapidly, and thus limits the changing of the charge by the vibration of the vibrator; this results in the development of the oscillatory voltage component across the capacity. Illustrative of the manner of employing the oscillatory variations in the voltage across the capacity, whichyof course also appear across the resistance B, I have shown connected across the latter the input circuit of a thermionic vacuum tube 3, whose cathode' may be energized in any suitable manner, as by battery l0. Included in this input circuit may be condensively by-passed resistance Il, across which the anode current of tube 9 may develop a small D. C. voltage for biasing the grid of the tube, as will be understood. The anode current supply for tube 9 may conveniently be a tap l2 on high voltage battery for source i; and the anode circuit may include the input of amplifier I3. The apparatus thus far described may advantageously be shielded by electro-static shielding schematically indicated as 3S, this shielding being connected, for example by the connection 35', to the junction between the battery l and resistance 8, or low potential side of the input circuit of tube 9.

lFrom the output of the amplier i3 may be provided in succession volume control It, further ampliiier l5 and loudspeaker or other electroacoustic translating device I5. Thus any oscillatory variations in the potential across the charged capacity may be amplified, controlled in respect of amplitude, and translated into sound.

The capacity from string to stud 2 being the charged capacity and the string being vibrated essentially parallel to the side of the stud, I have found that with the top of the stud well below the level of the string, as shown in Figure 2a, the translation characteristics are not materially different from those of a system in which the vibrator is vibrated toward and away from the conductive member. As the position of stud 2 relative to the string is raised, however, toward such a position as that shown in Figure 2, the translation characteristics are varied in such a manner a's progressively to increase the relative promt nenc'e of higher partial components in the output of loudspeaker it and to increase tendencies of the tone quality to change throughout the duration of the tone-i. e., certain characteristics peculiar to the output tones of the conventional piano are heightened. It will be seen from Figure 2 that the stud head or active portion is still assymetrically placed in a vertical direction with respect to the string; and in making the foregoing remarks I contemplate this limitation.

As shown in Figure 2, a greater portion of the rectangular head of the stud lies below the level of the string than lies above. rIhus an upward vibrational peak will carry the string, or tend to carry it, more completely clear of the studs than will a downward peak. The greater instantaneous capacity reduction and therefore greater instantaneous voltage rise will occur on the upward peak. For greatest emphasis of abrupt tone inception-a characteristic of the piano-I therefore prefer to make the initial displacement of the string an upward one, as by striking it from below by hammer 5. For reduction of this effect on the other hand, I may either strike the string from above, as alternatively indicated by harnmer 5 in Figure 3, or may reverse the positions of the studs to render their greater active portions above the strings. It will also be ound that some dierence in harmonic composition of the oscillations translated from any particular point along the string will exist, according as either the hammer or the greater portion of the stud is reversed from below to above the string. The desired harmonic structure being a matter o! choice in any event, this factor may readily be 5 determined by test in any particular case.

By setting switch 6 to connect stud 2', instead of string l, to battery 1,' the charged capacity becomes that between stud 2 and stud 2. While each electrode of this capacity is stationary, nev- 10 ertheless vibration of string I in the electrostatic field of the capacity will cause the voltage across it to vary oscillatorily. This is true for vibration either in a vertical or in a horizontal plane. This is the result of non-uniformity of the strength of 15 the leld intercepted by the string at its various instantaneous vibratory positions. This arrangement is therefore not limited to use with conductive strings, but is also useful with strings of material which is non-conductive but which has 20 a dielectricconstant appreciably diierent from unity.

If desired when employing a charged capacity neither of whose electrodes is the vibrator, such I as that between studs 2 and 2, the string may 25 be grounded as by switch l'i-i. e., connected to the low potential side of the input circuit of tube 9. Its vibration will still be eiciently translated.

It is therefore possible to exert individual control over the charges in the capacities respectively 3b associated with the several vibrators in a plural Vibrator instrument without insulating the vlbrators from each other; they may be connected together and to ground, the individual charge Y control being exerted by individual potential con'- 3.3 trol over an electrode of each yoi the several capacities. This has been schematically indicated in Figure la by potentiometers it individual to strings l, each of which potentiometers may control the potential of a stud 2', and hence their() charge in the capacity for the associated string l. It will be appreciated, of course, that the re= sult of individual charge control is control individual to the several `vibrators of the eclency of translation of their vibrations. The individc5 ual potentiometers may if desired be replaced by individual automatic potential control circuits, such as those shown in United States Patents Nos. 1,915,859 and 1,915,860 issued June 27, 1933, to myself and Charles T. Jacobs, for the production of organ-like tones.

In Figure la, as in Figure l,- the shielding is again shown, and may again be'connected by the connection 363' to the low potential side of the tube input circuit-i. e., to ground. The vl-` brators being connected to ground, it will be seen that the shielding is connected to the vla brators.

In Figures 4 and 5 I illustrate an instrument employing an electrostatic form oi translation 6U along the lines above described, by which a great variety of types of output tone may be produced. It will be understood that the particular arrangements shown in these figures are susceptible of considerable modification without alteration ci c5 the principles of operation, certain typical such modifications being illustrated in succeeding iig ures.

In Figures l and 5 will be seen two strings, i'

and l" respectively, for each note to be produced. Z0

These may be strung as conventionally in the piano and may thus be coupled together as by bridge i9, which may be supported by a plurality of vibratile ribs A2b, preferably slightly arched to=` ward the bridge. These ribs may for example to similar and similarly supported to the ribs customarily employed for reinforcement of the soundboard in the conventional piano; but no soundboard or other resonator need be therewith employed in the practice of the instant invention. This coupling together of the vibrators in an instrument ot this class has been disclosed and claimed in my co-pending application Serial Number 573,319, illedv November 6', 1931 (on which U. S. Patent No'. 1,929,029 has now been issued). It is to be understood that this coupling is not indispensible to the present invention, being illustrated to indicate a preference therefor. Thus the bridge i9 or its equivalent may if desired be entirely rigidly supported. The strings may be excited by hammers 5, which may in turn be actuated by a conventional key-operated action.

Studs 2 may be provided between the two strings of each note; and between strings of adjacent notes may be provided further studs,

those adjacent the strings being identified in Figure 4 as 2' and those adjacent the strings being identified as 2". The studs may be screwed for example into insulating strip I. The studs 2 may be electrically connectedtogether and to the pole of switch 2|; the studs 2' may be connected together and to the pole of switch 2|'; and the studs 2 may be connected together and to the pole of switch 2|". The frame or plate 24 oi' the instrument, with which all the strings l and i" may make electrical contact, may be connected to switch 22.

The pole of each of these switches may be selectively connected to the grid of tube 9, to a free potential (i. e., may be left effectively disconnected), to a potential highly negative with respect to ground (shown as the negative terminal of high voltage battery 1'), to a potential highly positive with respect to ground (shown as the positive terminal of high voltage battery l), or to ground. Ground, as in Figure 1, may designate the low potential side of the input circuit of tube 9, which tube may have associated with it high resistance 8 and condensively bypassed resistor as in Figure 1. A separate battery or other anode currentnsource 23 may be employed for tube 9, if desired; and the output of the tube may be supplied to further apparatus, such as that indicated in Figure 1.

Besides the switches 2|, 2|', 2| and 22, two other selective controls may be provided. First, by handle and rod 25, passing through elongated hole 26 in front rail 21 into base 28 of the action, the latter and hence hammers 5 may be shifted either to the left or right so that each strikes either the associated string or the associated stringi", instead of both. Secondly, by rotation of cam 29 about its pivot 30, bar 3| may be moved downwardly about its pivot 32 so that dampers 33 rest on the strings The points oi' contact of dampers 33 with the strings and the points of translation from the strings are preferably on opposite sides of the points of excitation-i. e., points of striking by hammers 5. Of course the arrangements shown for effecting the hammershift and the damping of one of the strings of each note are intended to be schematic, any of a variety of well-known structures being adaptable for each of these purposes.

It will be understood that string vibration will produce an oscillatory variation in all the several inter-element capacities existing between the strings, studs 2, studs 2 and studs 2 as the four respective elements (subject to the qualification that variation of the capacity between studs 2 and studs 2" will be negligible). It will further be seen that oscillatory variations in any of these capacities which may be charged through high resistance 8 will produce a corresponding A. C. voltage at the grid of tube 9. The function of the switches 22, 2|, 2| and 2|" is to charge the several inter-element capacities through resistance 8, selectively both with respect to the capacities themselves and with respect to the sign oi. the charges. four switches set as shown in Figure 4, the capacity between studs 2 and 2 is negatively charged through resistance 8 (by source and the capacity between studs 2 and 2 is similarly Thus for example with the 10 charged in like sign. Certain other capacities, 15

as that between studs 2' and the strings and that between studs 2" and the strings, will also be charged, but not through resistance 8--their charges are therefore not of significance in translating string vibrations into electric oscillations. 2O

Reversal of the sign of the charge in any of the capacities charged through resistance 8 will reverse the phase of the oscillations translated from vibratory variation thereof. Thus if only one of the four elements be connected to either 2o source 'l or source l', it may instead be connected to the other with no effect on the output sound waves excepting phase reversal. And the saine limitation of effect of sign reversal o1' charge to phase reversal of output sound obtains when 3o more than one o the four elements are connected to either, or respectively to both, oi' the sources i and l', provided such a reversal of the polarity oi one element is accompanied by a like reversal oi the polarity of the others. the poles of switches 2|' and 2| might each be moved downward one contact, polarizing studs 2' and 2" positively by connection to source i instead of negatively by connection to source 'l'. Another complete reversibility with no firstorder effect on output tone other than phase reversal is to be found when the charges of all the capacities charged through resistance 3 have the same sign-i. e., when one of the sources l and 'l' is without connection to any of the four elements'. 'Ihe element or elements connected to the grid of tube 9 may then be interchanged with those connected to the source i or 1 in use.

`.Thus in Figure 4 the pole of switch 2| might be moved downward two contacts and the poles of switches 2 and 2| upward two contacts. A second-order limitation on this general reversibility lies in the usual undesirability or connecting the large mass represented by the strings and frame of the instrument to the grid of the tube, because of dilculty in providing adequate electrostatic shielding for this mass without resultant excessive by-passing action.

In view of the reversibility of phase of oscillations by the sign 0f the charge in the capacity active in translating them, the translations respectively and simultaneously eiected by two or more capacities off, like charge may be said to be additive, and the translations respectively effected by two capacities of opposite charge may be said to be opposed. Thus in Figure 4, with switches 2| and 2|" respectively connecting studs 2' and 2" to the same source l as shown, the translations respectively eiected by the capacity from studs 2' to studs 2 and by the capacity from studs 2" to studs 2 may be considered additive. On the other hand, were the pole of one only oi.' the switches 2|' and 2| moved downward one contact, the translations Thus in Figure 4 35 would be opposed. It will be appreciated that reversal of the sign of the charge in one or more but less than all of the active capacities will usually produce far more significant eects on the output sound than mere phase reversal thereof, as will hereinafter more fully appear.

As shown in Figures 4 and 5, with hammers 5 striking both strings of each note, with dampers 33 inoperative, with studs 2 and 2"- similarly polarized, with studs 2 connected to the grid of tube 9, and with the strings grounded (or optionally free in potential), the controls are arranged for the production of a piano type of tone. It will be understood that translation is eected from the vibration of strings l' because of the interception thereby of the field of the charged capacity between studs 2 and studs 2, and from strings i" because of interception thereby of the eld of the charged capacity between studs 2" and studs 2. These translations from the two strings are seen to be additive, the studs 2' and studs 2" being similarly polarized; thus as long as the two strings of each note vibrate in phase with each other the translated oscillations will be additive.

Another switch setting which produces a piano type of tone, with the hammers striking both strings and the dempers iivinoperative, is one whereby the strings are polarized (by connection of the pole of switch 22 to source l or source 1'), and either the studs 2, or the studs 2' and 2", or all the studs are connected to the grid of tube e, any not so connected being grounded or free. Translation is in this case eiected by direct vibration of one element of the charged capacity.

For the elimination oi beats resulting from lack of perfect unison between the strings i' and l" `oi any note, or for other purposes, translation may be eiected if desired from one only of the strings for each note. This may readily be accomplished by the set-up shown in Figures 4 and 5, but with either studs 2 or studs 2 connected by their associated switch to ground (or to a free potential), stopping translation from strings l' or strings l respectively.

A slight variation of this limitation of activity to one string in producing electric oscillations may be obtained by employing the hammer shifting control 25 to move hammers 5 so that each strikes only one of its associated strings, translation being elected either from such one or additively from both of the strings. In the latter case, provided there be present inter-string coupling such as results from-the '.'ibratile support of bridge I9, some' vibration of the non-struck string of any played ote will be induced, as pointed out in my co-pending application Serial Number 583,613,1iled December 29, 1931, now Patent No. 1,933,295, granted October 31, 1933. As I therein showed, this vibration may tend to be out of phase with the vibration of the struckr string and to rise from zero to a nite value slowly rather than instantaneously. Thus with additive translation from opposed phase vibration of two strings, the oscillations respectively translated from the two strings will oppose each other; and because of the respective amplitude characteristics, the combined oscillations and hence the output tones will be characterized by a faster than normal decay. Again, the translation from the two strings may be made opposite instead or" additive, by oppositely polarizing the studs 2 and the studs 2". The result of opposite translation irom strings vibrating in opposite encima phase is of course additive oscillations; and be= cause of the respective amplitude characteristics in this case, the combined oscillations and hence the output tones will be characterized by a slower than normal decay. .;-5

'As I showed in the co-pending application last above referred to, if only one string of each note be struck and translation be effected only from the other, oscillations and a tone with a slow initial amplitude rise may be produced-i. e., an 10 organ-like tone. This is readily accomplished with the instrument herein shown, by striking for example only the strings i', connecting the studs 2' either to ground or to a free potential, and leaving strings, studs 2" and studs 2 con- 15 nected for example as respectively shown in Figure a.

These and various other eects which will suggest themselves may be selectively obtained with both strings undamped. By rotation oi cam 29, 2o

however, so that dampers 33 rest against the strings i", a wide further variety of eects may be 'secured Thus with strings l' damped, if both strings of each note are struck and strings l' and i" additively translated from, a generally piano- 25 like tone, but with an accentuated impact component, will be produced. Again, either both strings of each note or only the undamped strings i' may be struck, translation being eected only from the undamped strings l'; or only the strings 30 i' may be struck, translation being eected ad ditively from both strings. Any of these conditions of operation will produce only slight modiiicatons of a piano-like tone. Still again, either both strings of each note or only the damped 35 strings l" may be struck, translation being efe fected only from the damped strings i". Either of these conditions will produce a highly damped percussive tone. Another condition is one where in only the damped strings i" are struck, either f additive or opposed `translation being eected from both strings. in this casev before complete cessation of vibration of the damped string, it will have induced a small vibration of the undamped string i', so that the output tone com. prises a rapidly damped, percussive tone followed by a faint, slowly damped tone.

Opposed phase translation from the respective two strings oi each note, which will be understood to occur when studs 2' and 2" are `oppositely polarized, with strings i" damped also opens up further possibilities. Thus in the United States Patent No. 1,912,293, issued to me May 30, 1933, it was shown that by such translation from two substantially similarly tuned vibrators whose vibrations were at least in their inception in phase and one of'which .was preferably damped, organ-like tones might be secured. The instrument herein shown, with the controls as illustrated excepting that the pole o either; switch 2|' or 2i" is moved downward one contact and strings i" are damped, will operate in this manner. And as was pointed out in that patent, I have found the damping of the one string (1" herein) not indispensible to the obtainment of organ-like tones with the arrangement.

The last mentioned'condition of adjustment ci the switches is illustrated in Figure 6, wherein4 the strings and studs for a single note are sche matically shown in a View looking along the strings. A similarly taken view of an alternative embodiment of my invention is shown in Figure 6a, which is intended for optional substitution ior the left-hand portion of Figure t. Herein it is 352 35, 35' and 36" will be seen that studs 2' and 2" o! earlier iigures have been respectively replaced by studs or other conductive members 35 and 35". These instead of being essentially parallel to the planes of vibration of the strings l' and I", are respectively in those planes, so that the strings vibrate toward and away from them. All the various adjustments of switches, hammer-'shift and dampers abovementioned may still be employed to produce the various types of tones above analyzed; when studs 35 and/or 35" are elements of the active capacities, however, the translation characteristics in respect of prominence of upper partials, change of harmonic structure throughout tone duration, etc., will tend to be more nearly like those of a simple system wherein the vibratoi is one element or the active capacity and is vibrated toward and away from the other element.

mustrative of further possibilities of capacity arrangements, I have shown in Figure '7 two strings l and t", with studs 2, 2' and 2" as in earlier gures; with studs 35' and 35" as in Figure 6a; and with additional studs 36 and 36", similar to 35' and 35" but above instead of below the strings. Switches such as 2| are provided for connecting each selectively to any of the ve potentials as in previous igures. It will be understood that all seven studs need not be employed; thus a useful smaller number might be represented by the four studs 35', 35", 36' and 36". Very ne shades of translation and hence tone characteristics may be obtained with a.A

many-stud arrangement as illustrated, the principles of use thereof being, however, identical with those above disclosed for the various respective simpler arrangements.

Adjustment of the vertical separation of studs from the strings'will be understood to vary the amplitude of the oscillations translated from vibration of the string `at any given amplitude. Adjustment of the lateral separation of studs 2, 2' and 2" from the strings will produce a like variation, higher oscillation amplitudes being obtained with smaller separations, and vice versa..

It will of course be understood that there is intended no limitation of the invention to use with studs or any particular form of stud, the principles of the invention involving broadly any suitable members in the indicated spaced relationships to the strings or other vibrators, `and adapted to be inductively influenced by the latter.

It will finally be appreciated that the primary objects of the instant invention are concerned with tone characteristics other than predominate single harmonic structure. For the precise control of this latter characteristic in addition to the former, a .plurality of `systems each of the form herein disclosed Imay be employed at various points along the strings, and their outputs selectively combined, according to the principles set forth in the United States Patent No. 1,906,607, issued May 2, 1933, to Charles T. Jacobs. There may further or alternatively be employed a control over the absolute frequency characteristic of the electrical transmission system preceding loudspeaker I6, as disclosed and claimed in my co-pending application Serial Number 566,628, filed October 3, 1931 (on which U. S. Patent No. 1,929,028 has now been issued).

It is obvious that an instrument may be provided with less than all the selective controls illustrated and described, and still be capable of producing a large variety of the described effects.

Thus for example the dempers 33 may a' all times seat against the strings l", the selectively operable cam 29 for raising them being omitted or not used. Types of tone respectively requiring no damped string, or a damped string only, or a damped and an undamped string, may then of course be selectively obtained by shifting the hammers to strike respectively strings i only, strings I" only, or both strings l and l". At the same time the selective translating arrangements may be used, so that the total number of various tonal eilects obtainable will be large.

I claim:-

1. In a musical instrument, the combination of a vibrator; two stationary electrodes mutually forming an electrical capacity; means for charging said capacity; means for vibrating said vibrator to intercept at least a portion of the electrostatic eld across said capacity; means for hunting changes of the charge in said capacity by said vibration; and means responsive to oscillatory voltages appearing across said capacity.

2. In a. musical instrument, the combination of a tuned vibrator; two conductive members in spaced relation to said vibrator and forming electrical capacities with said vibrator and a capacity with each other; means selective with respect to a plurality of said capacities, including the capacity between said conductive members, for charging the same; means for vibrating said vibrator to disturb the electrostatic fields of said charged capacities; means for limiting changes of the charges in said capacities by said vibration; and means responsive to oscillatory voltages appearing across said charged capacities.

.3. In a musical instrument, the combination oi a plurality of tuned vibrators; conductive members, a respective two of said members being associated with each vibrator and forming with each other an electrical capacity individual to, and having when charged a ield at least partially intercepted by, said vibrator; individual circuits for charging the several said capacities; and means for limiting changes of the charges in said capacities by vibrator vibration.

4. In a musical instrument, the combination of a plurality of tuned vibrators; conductive members, a respective two of said members being associated with each vibrator and forming with each other an electrical capacity having when charged a field at least partially intercepted by said vibrator; means for maintaining charges in said capacities; means individually associated with said capacities for controlling the amplitudes of their several said charges; and means for limiting changes of said charges by vibrator vibration.

5. In a musical instrument, the combination of a plurality of tuned vibrators; means associated therewith for forming electrical capacities which are individual to the several said vibrators and which when charged have electrostatic elds varied by vibrations of the respective said vibrators; and ^means associated with said capacities for maintaining in each an electrical charge, said last mentioned means including a plurality oi.' means individual to the several said capacities for adjusting at will the relative amplitudes of their several said charges, and means for limiting changes of said charges by vibrator vibration.

6. In a musical instrument, the combination of a plurality of tuned strings lying substantially in a plane; means for vibrating said strings in planes essentially at right-angles to said firstmentioned plane; electrically conductive members between and having capacity to said strings, and intersected by said first-mentioned plane; means for maintaining electrical charges in the capacities between at least some of said conductive members and said strings; and means for limiting changes of said charges by string vibration.

7. In a musical instrument, the combination oi a plurality of tuned strings lying substantially in a plane; means for vibrating said strings in planes essentially at right-angles to said firstmentioned plane; electrically conductive members between said strings,4 intersected by said mst-mentioned plane, and forming capacities with each other; means for maintaining electrical charges in at least some of said capacities; and means for limiting changes of said charges by string vibration.

8. In a musical instrumenaithe combination or a relatively stationary member; a tuned vi.- brator in spaced relation thereto and means for vibrating said vibrator in a plane substantially parallel to the portion of said member nearest said vibrator, the mean position of said vibrator in the direction of its vibration being asymmetrical with respect to the extent of said portion in a like direction; and means associated with said member for producing electric oscillations in accordance with vibratory variations in the relative positions of said vibrator and said member.

9. Ina musical instrument including a tuned vibrator and means for producing vibration thereof essentially in a plane: a mechanico-electric translating system for translating said vibraiton into electric oscillations, said system including a member in spaced relation to and adapted to be inductively iniiuenced by said vibrator, and said member being disposed outside of said vibrational plane and arranged assymmetrically with respectto said vibrator in a direction parallel to that ci vibrator vibration.

lil. In a musical instrument including a tuned vibrator and vmeans for prcducing vibration thereof essentially in a plane: a mechain'co-electric translating system. for translating saicisviq bration into electric oscillations, said systemincluding a member in spaced relation to and adapted to be incluctively influenced by a portion of said vibrator, and said member being disposed outside of said Vibrational plane and substantially wholly on one side of a plane passed normal to said vibrational plane through said vibrator portion when in mean position.

il. 'I'he combination with. a musical instrument including a tuned vibrator, means for producing vibration of said vibrator essentially in a plane, and a mechanico-electric translating system having a portion in spaced relationship to and adapted to be inductively influenced by g said vibrator, said portion being disposed outside said vibrational plane:- of means for controlling qualitative characteristics of said oscillations, said controlling means comprising means included in said translating system for adjusting the l@ position of said portion in a path essentially parallel to the direction of vibration of said vibrator.

12. In a musical instrument of the type wherein vibration of a tuned vibrator is translated l5 into electric oscillations by oscillatory disturbance oi' the electrostatic field of a charged ca pacity, an electrode for such a capacity comprising a screw rotatably mounted in a line passing adjacent said vibrator, said screw having so a head of substantially rectangular cross-section.

13. In a musical instrument, the combination of two similarly tuned vibrators; selective means for exciting at will either one or both oi said vibrators and means for translating electric os- 2li cillations in opposite phase from the vibrations of said two vibrators respectively.

14. In a musical instrument, the combination of two similarly tuned vibrators; means selectively operable at will either to excite one only of said vibrators or to excite both simultaneously and similarly; means for translating electric osi cillations `from the vibrations of each of said two vibrators; and means for combining said oscillations in opposition to each other as respects their initial peaks.

l5. In a musical instrument, the combination of two similarly tuned vibrators; means selectively operable at will either to excite one only of said vibrators or to excite both simultaneously 40 and similarly; means for damping one of said vibrators; means for translating electric oscillations from the vibrations of each of said two vibrators; and means for combining said oscillations in opposition to each other as respects t5 their initial peaks. 16. A musical instrument having a series of mechanical vibratory members and electrodes located near the said vibratory members and forming electrical condensers together therewith, 50

and means for screening the electrodes.

17. A musical instrument according to claim 16 in which the screening means are electrically connected to the vibratory members. @s 

